Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

A method is provided for receiving broadcast signals. The broadcast signals are received. The received broadcast signals are demodulated by an Orthogonal Frequency Division Multiplex (OFDM) scheme, a signal frame is parsed from the demodulated broadcast signals, data is decoded in the parsed signal frame to output baseband packets, the baseband packets are output-processed to output link layer packets, and the link layer packets are de-encapsulated to output Transport Stream (TS) packets by inserting a header for each TS packet of which a header is deleted based on information of a header of the link layer packets.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/837,957, filed on Aug. 27, 2015 (now U.S. Pat. No. 9,614,642 issuedon Apr. 4, 2017), which claims the benefit of U.S. Provisional PatentApplication Nos. 62/126,690 and 62/098,348, filed on Mar. 1, 2015 andDec. 31, 2014, respectively, all of which are hereby expresslyincorporated by reference into the present application.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus fortransmitting broadcast signals and an apparatus for receiving broadcastsignals for future broadcast services and methods for transmitting andreceiving broadcast signals for future broadcast services.

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

To achieve the object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for receiving broadcast signals, the method comprises receivingthe broadcast signals, demodulating the received broadcast signals by anOFDM (Orthogonal Frequency Division Multiplex) scheme, parsing a signalframe from the demodulated broadcast signals, decoding data in theparsed signal frame and output-processing the decoded data.

The present invention can process data according to servicecharacteristics to control QoS (Quality of Services) for each service orservice component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2, including views (a) and (b), illustrates an input formattingblock according to one embodiment of the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 5, including views (a) and (b), illustrates a BICM block accordingto an embodiment of the present invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 10, including views (a), (b), (c) and (d), illustrates a framestructure according to an embodiment of the present invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIG. 19, including views (a) and (b), illustrates FIC mapping accordingto an embodiment of the present invention.

FIG. 20, including views (a) and (b), illustrates a type of DP accordingto an embodiment of the present invention.

FIG. 21, including views (a) and (b), illustrates DP mapping accordingto an embodiment of the present invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

FIG. 24, including views (a) and (b), illustrates a cell-worddemultiplexing according to an embodiment of the present invention.

FIG. 25, including views (a), (b) and (c), illustrates a timeinterleaving according to an embodiment of the present invention.

FIG. 26, including views (a) and (b), illustrates the basic operation ofa twisted row-column block interleaver according to an embodiment of thepresent invention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

FIG. 29 illustrates interleaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 30, including views (a) and (b), illustrates a protocol stackaccording to an embodiment of the present invention.

FIG. 31 illustrates an interface and an operation of the link layerincluded in the broadcast signal transmission apparatus according to anembodiment of the present invention.

FIG. 32 illustrates a broadcast signal transmission apparatus accordingto an embodiment of the present invention.

FIG. 33, including views (a) and (b), illustrates a structure of a linklayer packet according to an embodiment of the present invention.

FIG. 34, including views (a), (b) and (c), illustrates a structure ofthe link layer packet according to an embodiment of the presentinvention.

FIG. 35 illustrates a first header compression scheme according to anembodiment of the present invention.

FIG. 36 illustrates a TS packet header compressed by the first headercompression mode according to an embodiment of the present invention.

FIG. 37 illustrates a second header compression scheme according to anembodiment of the present invention.

FIG. 38 illustrates a TS packet header compressed by the second headercompression mode according to an embodiment of the present invention.

FIG. 39, including views (a) and (b), illustrates a compression schemeof the second header compression mode according to an embodiment of thepresent invention.

FIG. 40 illustrates a third header compression scheme according to anembodiment of the present invention.

FIG. 41 illustrates a TS packet header compressed by the third headercompression mode according to an embodiment of the present invention.

FIG. 42 illustrates a forth header compression scheme according to anembodiment of the present invention.

FIG. 43 illustrates a first null packet deletion scheme according to anembodiment of the present invention.

FIG. 44 illustrates a second null packet deletion scheme according to anembodiment of the present invention.

FIG. 45 illustrates a third null packet deletion scheme according to anembodiment of the present invention.

FIG. 46 illustrates a fourth null packet deletion scheme according to anembodiment of the present invention.

FIG. 47 illustrates an input format block according to anotherembodiment of the present invention.

FIG. 48 illustrates a broadcast signal reception apparatus according toan embodiment of the present invention.

FIG. 49 illustrates a packet configuration of a baseband frame accordingto an embodiment of the present invention.

FIG. 50, and FIG. 51 including views (a) and (b), illustrateconfigurations of a baseband frame according to an embodiment of thepresent invention.

FIG. 52 illustrates a packet configuration of a baseband frame accordingto another embodiment of the present invention.

FIG. 53, including views (a) and (b), illustrates a signaling field thatsignals a configuration of a baseband frame according to an embodimentof the present invention.

FIG. 54 illustrates a configuration of a baseband frame according to anembodiment of the present invention.

FIG. 55 illustrates a method of transmitting a broadcast signalaccording to an embodiment of the present invention.

FIG. 56 illustrates a method of receiving a broadcast signal accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles—base, handheld and advanced profiles—each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≦2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≦2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory size ≦2¹⁹ data cells Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame building block 1020, an OFDM (OrthogonalFrequency Division Multiplexing) generation block 1030 and a signalinggeneration block 1040. A description will be given of the operation ofeach module of the apparatus for transmitting broadcast signals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 including views (a) and (b), illustrates an input formattingblock according to one embodiment of the present invention. FIG. 2 showsan input formatting module when the input signal is a single inputstream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

FIG. 2(a) shows a mode adaptation block 2000 and a stream adaptation2010 for signal DP and FIG. 2(b) shows a PLS generation block 2020 and aPLS scrambler 2030 for generating and processing PLS data. A descriptionwill be given of the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 including views (a) and (b), illustrates a BICM block accordingto an embodiment of the present invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

FIG. 5(a) shows the BICM block shared by the base profile and thehandheld profile and FIG. 5(b) shows the BICM block of the advancedprofile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, el. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted bythe same carrier k and OFDM symbol 1 of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010 and aconstellation mapper 6020.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypuncturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS 1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS 1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permutted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.C _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ⁻¹,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  [Math figure 1]

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signaling K_(ldpc) code Type K_(sig) K_(bch) N_(bch)_parity(=N_(bch)) N_(ldpc) N_(ldpc)_parity rate Q_(ldpc) PLS1 342 1020 60 10804320 3240 1/4  36 PLS2 <1021 >1020 2100 2160 7200 5040 3/10 56

The LDPC parity puncturing block can perform puncturing on the PLS1 dataand PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data.

The constellation mapper 6020 can map the bit interleaved PLS1 data andPLS2 data onto constellations.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver 5050. In-band signaling data carriesinformation of the next TI group so that they are carried one frameahead of the DPs to be signaled. The Delay Compensating block delaysin-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI (programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

The OFDM generation block illustrated in FIG. 8 corresponds to anembodiment of the OFDM generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the OFDM generation block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots, continual pilots, edge pilots, FSS (frame signalingsymbol) pilots and FES (frame edge symbol) pilots. Each pilot istransmitted at a particular boosted power level according to pilot typeand pilot pattern. The value of the pilot information is derived from areference sequence, which is a series of values, one for eachtransmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9010 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9010 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9040 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9020 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9020 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9020 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9040.

The output processor 9030 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9030 can acquirenecessary control information from data output from the signalingdecoding module 9040. The output of the output processor 8300corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9040 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9010, demapping & decodingmodule 9020 and output processor 9030 can execute functions thereofusing the data output from the signaling decoding module 9040.

FIG. 10 including views (a), (b), (c) and (d), illustrates a framestructure according to an embodiment of the present invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. FIG. 10(a) shows a super frame according to an embodimentof the present invention, FIG. 10(b) shows FRU (Frame Repetition Unit)according to an embodiment of the present invention, FIG. 10(c) showsframes of variable PHY profiles in the FRU and FIG. 10(d) shows astructure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts: PLS2-STAT data andPLS2-DYN data. The static and dynamic portion of PLS2 data is followedby padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00  8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 ⅕ 001 1/10 010 1/20 011 1/40 100 1/80 1011/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current PHY_PROFILE = PHY_PROFILE = CurrentPHY_PROFILE = ‘001’ ‘010’ PHY_PROFILE = ‘000’ (base) (handheld)(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile present profile present profile presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU. Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Content PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2 NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15  0110 11/15  0111 12/15  1000 13/15  1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI=1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (PI=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 2-bit field P_(I) N_(TI) 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver 5050. If time interleaving is not used for a DP, it is setto ‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE ValueIs TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6 Reserved 10Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bit 15 bitHandheld — 13 bit Advanced 13 bit 15 bit

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) NFSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 including views (a) and (b), illustrates FIC mapping accordingto an embodiment of the present invention.

FIG. 19(a) shows an example mapping of FIC cell without EAC and FIG.19(b) shows an example mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example inFIG. 19(a). Depending on the FIC data size, FIC cells may be mapped overa few symbols, as shown in FIG. 19(b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20, including views (a) and (b), illustrates a type of DP accordingto an embodiment of the present invention.

FIG. 20(a) shows type 1 DP and FIG. 20(b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:D _(DP1) +D _(DP2) ≦D _(DP)  [Expression 2]

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 including views (a) and (b), illustrates DP mapping according toan embodiment of the present invention.

FIG. 21(a) shows an addressing of OFDM cells for mapping type 1 DPs andFIG. 21(b) shows an addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1-1) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2-1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch) − K_(bch) 5/15 64800 21600 21408 12 192 6/15 2592025728 7/15 30240 30048 8/15 34560 34368 9/15 38880 38688 10/15  4320043008 11/15  47520 47328 12/15  51840 51648 13/15  56160 55968

TABLE 29 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch) − K_(bch) 5/15 16200 5400 5232 12 168 6/15 6480 63127/15 7560 7392 8/15 8640 8472 9/15 9720 9552 10/15  10800 10632 11/15 11880 11712 12/15  12960 12792 13/15  14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow expression.B _(ldpc) =[I _(ldpc) P _(ldpc) ]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldoc) ⁻¹,p ₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹]  [expression3]

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate Nldpc−Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(−K) _(ldpc) ⁻¹=0  [expression4]

2) Accumulate the first information bit—i0, at parity bit addressesspecified in the first row of an addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:p ₉₈₃ =p ₉₈₃ ⊕i ₀ p ₂₈₁₅ =p ₂₈₁₅ ⊕i ₀p ₄₈₃₇ =p ₄₈₃₇ ⊕i ₀ p ₄₉₈₉ =p ₄₉₈₉ ⊕i ₀p ₆₁₃₈ =p ₆₁₃₈ ⊕i ₀ p ₆₄₅₈ =p ₆₄₅₈ ⊕i ₀p ₆₉₂₁ =p ₆₉₂₁ ⊕i ₀ p ₆₉₇₄ =p ₆₉₇₄ ⊕i ₀p ₇₅₇₂ =p ₇₅₇₂ ⊕i ₀ p ₈₂₆₀ =p ₈₂₆₀ ⊕i ₀p ₈₄₉₆ =p ₈₄₉₆ ⊕i ₀  [expression 5]

3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulateis at parity bit addresses using following expression.{x+(s mod 360)×Q _(ldpc)} mod(N _(lpdc) −K _(ldpc))  [expression 6]

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit i1, thefollowing operations are performed:p ₁₀₀₇ =p ₁₀₀₇ ⊕i ₀ p ₂₈₃₉ =p ₂₈₃₉ ⊕i ₀p ₄₈₆₁ =p ₄₈₆₁ ⊕i ₀ p ₅₀₁₃ =p ₅₀₁₃ ⊕i ₀p ₆₁₆₂ =p ₆₁₆₂ ⊕i ₀ p ₆₄₈₂ =p ₆₄₈₂ ⊕i ₀p ₆₉₄₅ =p ₆₉₄₅ ⊕i ₀ p ₆₉₉₈ =p ₆₉₉₈ ⊕i ₀p ₇₅₉₆ =p ₇₅₉₆ ⊕i ₀ p ₈₂₈₄ =p ₈₂₈₄ ⊕i ₀p ₈₅₂₀ =p ₈₅₂₀ ⊕i ₀  [expression 7]

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the expression 6, where x denotes the addressof the parity bit accumulator corresponding to the information bit i360,i.e., the entries in the second row of the addresses of parity checkmatrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1p _(i) =p _(i) ⊕p _(i-1) ,i=1,2, . . . ,N _(ldpc) −K _(ldpc)−1  [Mathfigure 8]

where final content of pi, i=0, 1, . . . , Nldpc−Kldpc−1 is equal to theparity bit pi.

TABLE 30 Code Rate Q_(ldpc) 5/15 120 6/15 108 7/15 96 8/15 84 9/15 7210/15  60 11/15  48 12/15  36 13/15  24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Q_(ldpc) 5/15 30 6/15 27 7/15 24 8/15 21 9/15 1810/15  15 11/15  12 12/15  9 13/15  6.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-groupinterleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/η mod or 16200/η mod according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (η mod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type η_(mod) N_(QCB)_IG QAM-16 4 2 NUC-16 4 4 NUQ-646 3 NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 10 10.

The inner-group interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 including views (a) and (b), illustrates a cell-worddemultiplexing according to an embodiment of the present invention.

FIG. 24(a) shows a cell-word demultiplexing for 8 and 12 bpcu MIMO andFIG. 24(b) shows a cell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,1, c1,1, . . . , c η mod−1,1) of the bit interleavingoutput is demultiplexed into (d1,0,m, d1,1,m . . . , d1, η mod−1,m) and(d2,0,m, d2,1,m . . . , d2, η mod−1,m) as shown in (a), which describesthe cell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c0,1, c1,1, . . . , c9,1) of the Bit Interleaver output isdemultiplexed into (d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m, d2,1,m .. . , d2,5,m), as shown in (b).

FIG. 25, including views (a), (b) and (c), illustrates a timeinterleaving according to an embodiment of the present invention.

FIGs. (a) to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks NTI per TI group. For DP_TI_TYPE=‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_(allowed values: 1, 2, 4, 8): Represents the number of theframes IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI), where each TI block corresponds to one usage of time interleavermemory. The TI blocks within the TI group may contain slightly differentnumbers of XFECBLOCKs. If the TI group is divided into multiple TIblocks, it is directly mapped to only one frame. There are three optionsfor time interleaving (except the extra option of skipping the timeinterleaving) as shown in the below table 33.

TABLE 33 Modes Descriptions Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_LENGTH = ‘1’(N_(TI) = 1). Option-2 Each TI group contains one TI block and is mappedto more than one frame. (b) shows an example, where one TI group ismapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Option-3 Each TI group is divided into multiple TIblocks and is mapped directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_LENGTH = N_(TI), while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d_(n,s,0,0),d_(n,s,0,1), . . . , d_(n,s,0,N) _(cells) ⁻¹,d_(n,s,1,0), .. . , d_(n,s,1,N) _(cells) ⁻¹, . . . , d_(n,s,N) _(xBLOCK—TI)_((n,s)−1,0), . . . ,d_(n,s,N) _(xBLOCK—TI) _((n,s)−1,N) _(cells−1) ),

where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group and represents the outputs of SSD and MIMOencodings as follows

$d_{n,s,r,q} = \{ {\begin{matrix}{f_{n,s,r,q},} & {{the}\mspace{14mu}{output}\mspace{14mu}{of}\mspace{14mu} S\; S\; D\mspace{14mu}\ldots\mspace{14mu}{encoding}} \\{g_{n,s,r,q},} & {{the}\mspace{14mu}{output}\mspace{14mu}{of}\mspace{14mu}{MIMO}\mspace{14mu}{encoding}}\end{matrix}.} $

In addition, assume that output XFECBLOCKs from the time interleaver5050 are defined as

(H_(n,s,0), H_(n,s,1), . . . , h_(n,s,i), . . . , h_(n,s,N) _(xBLOCK—TI)_((n,s)×N) _(cells) ⁻¹),

where h_(n,s,i) is the ith output cell (for i=0, . . . , N_(xBLOCK) _(_)_(TI)(n, s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK) _(_) _(TI)(n, s).

FIG. 26, including views (a) and (b), illustrates the basic operation ofa twisted row-column block interleaver according to an embodiment of thepresent invention.

FIG. 26 (a) shows a writing operation in the time interleaver and FIG.26(b) shows a reading operation in the time interleaver The firstXFECBLOCK is written column-wise into the first column of the TI memory,and the second XFECBLOCK is written into the next column, and so on asshown in (a). Then, in the interleaving array, cells are read outdiagonal-wise. During diagonal-wise reading from the first row(rightwards along the row beginning with the left-most column) to thelast row, N_(r), cells are read out as shown in (b). In detail, assumingz_(n,s,i) (i=0, . . . , N_(r), N_(c)) as the TI memory cell position tobe read sequentially, the reading process in such an interleaving arrayis performed by calculating the row index R_(n,s,i), the column indexC_(n,s,i), and the associated twisting parameter T_(n,s,i) as followsexpression.

$\begin{matrix}{{{GENERATE}( {R_{n,s,i},C_{n,s,i}} )} = \{ {{R_{n,s,i} = {{mod}\;( {i,N_{r}} )}},{T_{n,s,i} = {{mod}( {{S_{shift} \times R_{n,s,i}},N_{c}} )}},{C_{n,s,i} = {{mod}\;( {{T_{n,s,i} + \lfloor \frac{i}{N_{r}} \rfloor},N_{c}} )}}} \}} & \lbrack {{expression}\mspace{14mu} 9} \rbrack\end{matrix}$

where S_(shift) is a common shift value for the diagonal-wise readingprocess regardless of N_(xBLOCK) _(_) _(TI)(n, s), and it is determinedby N_(xBLOCK) _(_) _(TI) _(_) _(MAX) given in the PLS2-STAT as followsexpression.

                                    [expression  10]   for $\{ {\begin{matrix}{{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} = {N_{{xBLOCK\_ TI}{\_ MAX}} + 1}},} & {{{if}\mspace{14mu} N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime}{mod}\; 2} = 0} \\{{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} = N_{{xBLOCK\_ TI}{\_ MAX}}},} & {{{if}\mspace{14mu} N_{{xBLOCK\_ TI}{\_ MAX}}{mod}\; 2} = 1}\end{matrix},\mspace{20mu}{S_{shift} = \frac{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} - 1}{2}}} $

As a result, the cell positions to be read are calculated by acoordinate as z_(n,s,i)=N_(r)C_(n,s,i)+R_(n,s,i).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

More specifically, FIG. 27 illustrates the interleaving array in the TImemory for each TI group, including virtual XFECBLOCKs when N_(xBLOCK)_(_) _(TI)(0,0)=N_(xBLOCK) _(_) _(TI)(1,0)=6, N_(xBLOCK) _(_) _(TI)(2,0)=5.

The variable number N_(xBLOCK) _(_) _(TI)(n, s)=N_(r) will be less thanor equal to N′_(xBLOCK) _(_) _(TI) _(_) _(MAX). Thus, in order toachieve a single-memory deinterleaving at the receiver side, regardlessof N_(xBLOCK) _(_) _(TI)(n, s), the interleaving array for use in atwisted row-column block interleaver is set to the size ofN_(r)×N_(c)=N_(cells)×N′_(xBLOCK) _(_) _(TI) _(_) _(MAX) by insertingthe virtual XFECBLOCKs into the TI memory and the reading process isaccomplished as follow expression.

[expression11] p = 0; for i = 0;i < N_(cells)N′_(xBLOCK)_TI_MAX;i = i +1 {GENERATE(R_(n,s,i),C_(n,s,i)); V_(i) = N_(r)C_(n,s,j) + R_(n,s,j) ifV_(i) < N_(cells)N_(xBLOCK)_TI(n,s) { Z_(n,s,p) = V_(i); p = p + 1; } }

The number of TI groups is set to 3. The option of time interleaver issignaled in the PLS2-STAT data by DP_TI_TYPE=‘0’, DP_FRAME_INTERVAL=‘1’,and DP_TI_LENGTH=‘1’, i.e., NTI=1, IJUMP=1, and PI=1. The number ofXFECBLOCKs, each of which has Ncells=30 cells, per TI group is signaledin the PLS2-DYN data by NxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, andNxBLOCK_TI(2,0)=5, respectively. The maximum number of XFECBLOCK issignaled in the PLS2-STAT data by NxBLOCK_Group_MAX, which leads to└N_(xBLOCK) _(_) _(Group) _(_) _(MAX)/N_(TI)┘=N_(xBLOCK) _(_) _(TI) _(_)_(MAX)=6.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

More specifically FIG. 28 shows a diagonal-wise reading pattern fromeach interleaving array with parameters of N′_(xBLOCK) _(_) _(TI) _(_)_(MAX)=7 and Sshift=(7−1)/2=3. Note that in the reading process shown aspseudocode above, if V_(i)≧N_(cells)N_(xBLOCK) _(_) _(TI)(n, s), thevalue of Vi is skipped and the next calculated value of Vi is used.

FIG. 29 illustrates interleaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 29 illustrates the interleaved XFECBLOCKs from each interleavingarray with parameters of N′_(xBLOCK) _(_) _(TI) _(_) _(MAX)=7 andSshift=3.

FIG. 30, including views (a) and (b), illustrates a protocol stackaccording to an embodiment of the present invention. As illustrated inFIG. 30(a), a link layer may perform link layer signaling,encapsulation, and/or overhead reduction. The link layer may performoverhead reduction and encapsulation on a packet received from an upperlayer to deliver the packet to a physical layer. The present inventionproposes a configuration of the link layer of the protocol stack andproposes a scheme of delivering an MPEG-2 TS packet which is deliveredfrom an upper layer to a physical layer. In the present invention, thebroadcast signal transmission apparatus may encapsulate the MPEG-2 TSpacket in the link layer and deliver the packet to the physical layer.The broadcast signal transmission apparatus may perform overheadreduction on the MPEG-2 TS packet in the link layer, thereby efficientlyusing radio resources.

The link layer may be referred to as an encapsulation layer or a layer2. Hereinafter, a description will be given using the term link layer.In actual application of the present invention, the above other termsmay be used instead or a new name may be applied.

FIG. 30(b) illustrates a flow of data between layers in the broadcastsignal transmission apparatus and the broadcast signal receptionapparatus. The broadcast signal transmission apparatus may use an IPand/or MPEG-2 TS packet, which is used in digital broadcasting, as inputdata.

The IP and/or MPEG-2 TS packet input to the broadcast signaltransmission apparatus may be delivered to the physical layer throughthe link layer. The physical layer may have difficulty in adaptivelyprocessing packets for various protocols. Therefore, the link layer ofthe broadcast signal transmission apparatus may encapsulate packetswhich use different protocols in packets having a constant format anddeliver the encapsulated packet to the physical layer. This process maybe defined as encapsulation. To efficiently use radio resources in theencapsulation process, the link layer may use an overhead reductionscheme suitable for an upper layer protocol corresponding to eachpacket. A link layer signal and data encapsulated in the link layer aredelivered to the physical layer, and the physical layer may transmit abroadcast signal through the above-described process. Here, the linklayer signal may include the following three types of signalinginformation. First signaling information is signaling information whichis delivered from an upper layer to the link layer and to be deliveredto an upper layer of the broadcast signal reception apparatus. Secondsignaling information corresponds to a signal which is generated in thelink layer to provide information for data processing of a link layer ofthe broadcast signal reception apparatus. Third signaling information isgenerated in the upper layer or the link layer. However, the thirdsignaling information corresponds to a signal delivered for rapiddetection of a broadcast signal in the physical layer.

The broadcast signal reception apparatus may restore data and signals,delivered from the physical layer, to data formats processable in anupper layer and deliver the restored data and signals. In this instance,it is possible to verify whether a packet delivered from the physicallayer is a signal or data by reading a header of the packet or usinganother scheme. In addition, a delivered signal may be used to restore apacket, overhead of which is reduced, to an original packet.

FIG. 31 illustrates an interface and an operation of the link layerincluded in the broadcast signal transmission apparatus according to anembodiment of the present invention. An IP packet may be subjected to anoverhead reduction function and encapsulated and then delivered to thephysical layer, or directly encapsulated without being subjected to theoverhead reduction function and delivered to the physical layer.

An MPEG-2 TS packet is subjected to the overhead reduction function,encapsulated, and then delivered to the physical layer. The MPEG-2 TSpacket may be directly encapsulated without being subjected to theoverhead reduction function. However, exclusion of fixed overhead suchas sync byte (0x47), etc. positioned at a head of the packet may assistin efficiently using a resource in a radio interval. The overheadreduction function to be described below may be applied to the headercompression block 3040 described with reference to FIG. 3.

Even when a packet delivered through the link layer is not the IP orMPEG-2 TS packet, the packet may be delivered to the physical layerthrough a similar process to that of the IP packet. In this instance,whether to apply the overhead reduction function to the packet may bedetermined according to characteristics of the packet.

The broadcast signal transmission apparatus reduces a size of an inputpacket using a scheme corresponding to the packet in an overheadreduction process. The broadcast signal transmission apparatus mayextract and generate particular information related to overheadreduction in the overhead reduction process, and transmit the particularinformation through signaling. The signaling enables a receiver torestore a packet changed in the overhead reduction process to anoriginal packet to be transmitted.

A signal may be transmitted and the transmission may be managed in thelink layer of the broadcast signal transmission apparatus. In addition,a signaling transmission module may be configured according tophysically and logically separated transmission paths in the physicallayer of the broadcast signal transmission apparatus, and a signal whichis not transmitted through a particular transmission path may beencapsulated and transmitted through a physical layer pipe (PLP). ThePLP corresponds to a logical unit for transmission of data in thephysical layer, and may be referred to as the data pipe described above.As described in the foregoing, a signal managed in the link layer mayinclude information delivered from an upper layer, a system parameter, asignal generated in the link layer, etc.

FIG. 32 illustrates a broadcast signal transmission apparatus accordingto an embodiment of the present invention. The broadcast signaltransmission apparatus may include a link layer (L2) encapsulator 32010,an input formatter 32020, an interleaver and encoder 32030, a framebuilder 32040, and/or a modulator 32050. In the present invention, theL2 encapsulator 32010 may perform overhead reduction on a packetdelivered from an upper layer, and then output the packet to the inputformatter 32020 which belongs to a physical layer. The input formatter32020 may output an input stream in PLPs, and the interleaver andencoder 32030 may interleave and encode input PLP data. In addition, theframe builder 32040 may build a frame using the encoded PLP data, andthe modulator 32050 may generate and transmit a broadcast signal usingan OFDM modulation scheme. The broadcast signal transmission apparatusmay transmit the broadcast signal using a transmitter.

An input signal input to the input formatter 32020 may correspond to atransport stream (TS), an IP stream, and a general stream (GS), and theL2 encapsulator 32010 may encapsulate the input signal according to anL2 structure to generate a GS.

The L2 encapsulator 32010 included in the broadcast signal transmissionapparatus of the present invention may receive a TS to generate a GSusing a technology of compressing a TS header and deleting a nullpacket. In this way, the broadcast signal transmission apparatus mayperform more efficient transmission when compared to a scheme ofdirectly inputting a TS to the input formatter 32020.

FIG. 33, including views (a) and (b), illustrates a structure of a linklayer packet according to an embodiment of the present invention.

A link layer is an upper layer of a physical layer. In a broadcastsystem, generic stream encapsulation (GSE), a type-length-value (TLV)structure, and a basic broadcast protocol (BBP) correspond to the linklayer. The link layer packet has a fixed header of a fixed size and mayhave a structure including an extended header of a variable sizeaccording to a configuration of the packet. A payload including datareceived from an upper layer may be positioned at a tail of a basicheader and the extended header of the link layer packet.

A header of the link layer packet may include a field that indicates atype of the payload included in the packet. In the fixed header, thefirst 3 bits may designate a packet type of an upper layer. In otherwords, the link layer packet starts with a type field (3 bits) asillustrated in FIG. 33(a), and the type field may signal a type of astream encapsulated by the link layer as illustrated in FIG. 33(b).

For example, the type field may be set to a value of 000 when the linklayer packet encapsulates an IPv4 packet, and the type field may be setto a value of 010 when the link layer packet encapsulates an MPEG-2 TS.

FIG. 34, including views (a), (b) and (c), illustrates a structure ofthe link layer packet according to an embodiment of the presentinvention.

The broadcast signal transmission apparatus may use the structure of thelink layer packet as in FIG. 34(a) to transmit an MPEG-2 TS. The linklayer packet may include a type field, an HC_mode field, an NPD modefield, an ISSYI field, a Num_TS field, an ISSY field and/or a payload.The broadcast signal transmission apparatus may set the type field ofthe link layer packet which transmits the TS to 010. In other words, thetype field may indicate that a payload transmitted through the linklayer packet is a TS packet. The link layer packet may configure fieldspositioned subsequent to the type field as fields for transmission ofthe TS. In other words, the link layer packet may include the HC_modefield, the NPD_mode field, and the Num_TS field corresponding to thefields for transmission of the TS.

The HC_mode field has 2 bits, and may include information about a headercompression mode of the TS packet transmitted through the payload. Asillustrated in FIG. 34(b), the header compression mode may include fourmodes. When a value of the HC_mode field is 00, the value indicatesHC_mode1, and a header of the TS of 188 bytes may be compressed bydeleting Sync byte (0x47) included in the header. The broadcast signaltransmission apparatus may compress a length of the header correspondingto 188 bytes into 187 bytes through HC_mode1. When a value of theHC_mode field is 01, the value indicates HC_mode2, and the header may becompressed by compressing a PID (13 bits). HC_mode2 may include a schemeof deleting Sync byte (0x47) of HC_mode1. The broadcast signaltransmission apparatus may compress a length of the header correspondingto 188 bytes into 186 bytes through HC_mode2. When a value of theHC_mode field is 10, the value indicates HC_mode3. When a PID of the TSto be transmitted is the same as another PID, a header may be compressedby deleting the PID (13 bits). HC_mode3 may include a scheme of deletingSync byte (0x47) of HC_mode1. The broadcast signal transmissionapparatus may compress a length of the header corresponding to 188 bytesinto 185 bytes through HC_mode3. When a value of the HC_mode field is11, the value indicates HC_mode4. When all fields in addition to a PIDof the TS to be transmitted are the same as other fields and anotherPID, the header may be compressed by deleting a TS header. HC_mode4 mayinclude a scheme of deleting Sync byte (0x47) of HC_mode1. The broadcastsignal transmission apparatus may compress a length of the headercorresponding to 188 bytes into 184 bytes through HC_mode4.

The NPD_mode field has 2 bits, and may include information about a nullpacket deletion mode of the TS transmitted through the payload. Asillustrated in FIG. 34(c), the null packet deletion mode may includefour modes. When a value of the NPD_mode field is 00, null packets maybe transmitted without being deleted. When a value of the NPD_mode fieldis 01, null packets are deleted, and the number of deleted null packetsmay be indicated by inserting a DNP (8 bits) into a tail of each TSpacket. When a value of the NPD_mode field is 10, a series of TS packetsis transmitted until a null packet appears. When the null packetappears, the null packet may be deleted and a 1-byte DNP may be insertedinto a tail of an L2 payload. This scheme may be used in a case of a lowfrequency of null packets. When a value of the NPD_mode field is 11, aseries of TS packets is transmitted until a null packet appears. Whenthe null packet appears, the null packet may be deleted and a 2-byte DNPmay be inserted into a tail of the L2 payload. This scheme may be usedin a case of a low frequency of null packets.

The ISSYI field has 1 bit, and may include information that indicateswhether the ISSY field is used. When a value of the ISSYI field is 0,the ISSY field may not be used and an L2 header may have 2 bytes. When avalue of the ISSYI field is 1, the ISSYI field may be present, and theISSYI field may transmit an ISSY value of an initial TS packet accordingto an ISSY field rule used in DVB-T2.

The Num_TS field has 8 bits, and may signal the number of TS packetsencapsulated in the link layer.

FIG. 35 illustrates a first header compression scheme according to anembodiment of the present invention. A first header compression mode maybe expressed by HC_mode1. When a header compression mode used for a linklayer packet is HC_mode1, a value of the HC_mode field may be set to 00.In addition, a TS packet of 187 bytes configured by excluding Sync bytefrom a TS packet of 188 bytes may be included in a payload of the linklayer packet. In this case, a length of the payload is 187*Num_TS, and atotal length of the link layer packet may be obtained by adding thelength of the payload to a length of an L2 header (2 or 5 bytes). Inother words, a TS packet header corresponding to a portion ofinformation transmitted through the payload may be compressed from 4bytes into 3 bytes and transmitted. As described in the foregoing, theNum_TS field may indicate the number of TS packets encapsulated in thelink layer.

FIG. 36 illustrates a TS packet header compressed by the first headercompression mode according to an embodiment of the present invention. Asillustrated in the figure, a TS packet header to be subjected to headercompression may include Sync Byte, transport error indicator (TE),payload unit start indicator (SI), transport priority (TP), PID,scrambling control (SC), adaptation field control (AF) and/or continuitycounter (CC) fields. The broadcast signal transmission apparatus of theinvention may delete Sync Byte using HC_mode1 which is the first headercompression mode. Therefore, after header compression, the TS packetheader may include the TE, SI, TP, PID, SC, AF and/or CC fields. Inother words, the broadcast signal transmission apparatus does nottransmit Sync Byte in HC_mode1. In this way, the TS packet header of 4bytes may be compressed into 3 bytes.

FIG. 37 illustrates a second header compression scheme according to anembodiment of the present invention. A second header compression modemay be expressed by HC_mode2. When a header compression mode used forthe link layer packet is HC_mode2, a value of the HC_mode field may beset to 01. In addition, a first TS packet having 187 bytes which isobtained by excluding Sync byte from a TS packet of 188 bytes may beincluded in a payload of the link layer packet. From a second TS packetincluded in the payload, a TS packet may have a total length of 186bytes which includes 2 bytes of a TS header. In other words, inHC_mode2, a broadcast signal transmitter may compress a PID into asub-PID for TS packets excluding the first TS packet included in thepayload. The broadcast signal transmitter may compress a PID of 13 bitsinto a sub-PID of 8 bits.

In this case, a length of the payload is 186*Num_TS+1 bytes, and a totallength of the link layer packet may be obtained by adding the length ofthe payload to a length of an L2 header (2 or 5 bytes). In other words,in information transmitted through the payload, a first TS packet headermay be compressed from 4 bytes into 3 bytes, and each of the other TSpacket headers may be compressed from 4 bytes into 2 bytes andtransmitted. As described in the foregoing, the Num_TS field mayindicate the number of TS packets encapsulated in the link layer.

FIG. 38 illustrates a TS packet header compressed by the second headercompression mode according to an embodiment of the present invention. Asillustrated in the figure, a TS packet header to be subjected to headercompression may include Sync Byte, TE, SI, TP, PID, SC, AF and/or CCfields. The broadcast signal transmission apparatus of the presentinvention may delete Sync Byte and compress a PID using HC_mode2 whichis the second header compression mode. Therefore, after headercompression, the TS packet header may include TE, SI, TP, sub-PID, SC,AF and/or continuity counter sync flag (SF) fields. In other words, thebroadcast signal transmission apparatus does not transmit Sync Byte andcompresses the PID in HC_mode2. In this way, the TS packet header of 4bytes may be compressed into 2 bytes. The broadcast signal transmissionapparatus may use an indicator and an index value when compressing thePID of 13 bits. In other words, the broadcast signal transmissionapparatus may configure a sub-PID using a PSI indicator of 1 bit and anindex of 7 bits. In other words, the PID of 13 bits may be compressedinto a sub-PID of 8 bits through header compression. In addition, thebroadcast signal transmission apparatus may replace the CC field withthe SF field in HC_mode2. The broadcast signal transmission apparatusmay further reduce 3 bits by replacing the CC field of 4 bits with theSF field of 1 bit. The broadcast signal transmission apparatus mayreduce 2 bytes (16 bits) from the TS packet header to be subjected tocompression by deleting Sync Byte to reduce 8 bits, compressing the PIDto reduce 5 bits, and replacing the CC field to reduce 3 bits for the TSpacket header. In other words, the TS packet header of 4 bytes may becompressed into 2 bytes.

FIG. 39, including views (a) and (b), illustrates a compression schemeof the second header compression mode according to an embodiment of thepresent invention. A sub-PID may include a PSI indicator of 1 bit and anindex of 7 bits. As illustrated in FIG. 39(a), when the PSI indicator ofthe sub-PID corresponds to a value of 1, the index of 7 bits may have aPID of a PSI packet defined in advance. For example, when a packet to betransmitted is a PAT (PID=0), the broadcast signal transmissionapparatus may set the PSI indicator included in the sub-PID to 1 and setthe index to 000000, thereby transmitting the packet. In this case, thebroadcast signal reception apparatus may decompress a sub-PID of 1000000into 0x0000 which is a PID of a PAT using a predetermined table. Inother words, when the PSI indicator is 1, it is possible to directlyidentify a PSI or PSIP table corresponding to information included inthe packet using an index value.

On the other hand, when a data PID is compressed, the broadcast signaltransmission apparatus sets the PSI indicator to 0, and the indexexpresses an offset with respect to a PID transmitted as the first 3bytes by sign bits of 7 bits. For example, in a TS including a number100 (video) PID and a number 102 (audio) PID, when the number 100 PID istransmitted in a TS header of the first 3 bytes included in a link layerpacket, indices included in sub-PIDs of subsequent TS packets of thenumber 100 PID and the number 102 PID may be expressed by 0 and 2.

The broadcast signal reception apparatus may obtain an actually desiredPID by adding an index value to a first received PID in the link layerpacket.

Even though a continuity counter has 4 bytes, the continuity counter maybe initially transmitted once. From a second packet, a continuitycounter may be compressed into a continuity counter sync flag of 1 bit.As illustrated in FIG. 39(b), the continuity counter sync flag may beexpressed by 1 when the continuity counter is 0000, and expressed by 0otherwise.

FIG. 40 illustrates a third header compression scheme according to anembodiment of the present invention. A third header compression mode maybe expressed by HC_mode3. When a header compression mode used for thelink layer packet is HC_mode3, a value of the HC_mode field may be setto 10. In addition, a first TS packet having 187 bytes which is obtainedby excluding Sync byte from a TS packet of 188 bytes may be included ina payload of the link layer packet. From a second TS packet included inthe payload, a TS packet may have a total length of 185 bytes whichincludes 1 byte of a TS header. In other words, in HC_mode3, a broadcastsignal transmitter may delete PIDs of TS packets excluding the first TSpacket included in the payload. This scheme may be used when TS packetsincluded in the link layer packet have the same PID. In other words, thescheme may be used when a PID among a plurality of fields included inthe TS header is the same and the other fields are different between theTS packets.

In this case, a length of the payload is 185*Num_TS+2 bytes, and a totallength of the link layer packet may be obtained by adding the length ofthe payload to a length of an L2 header (2 or 5 bytes). In other words,in information transmitted through the payload, a first TS packet headermay be compressed from 4 bytes into 3 bytes, and each of the other TSpacket headers may be compressed from 4 bytes into 1 byte andtransmitted. As described in the foregoing, the Num_TS field mayindicate the number of TS packets encapsulated in the link layer.

FIG. 41 illustrates a TS packet header compressed by the third headercompression mode according to an embodiment of the present invention. Asillustrated in the figure, a TS packet header to be subjected to headercompression may include Sync Byte, TE, SI, TP, PID, SC, AF and/or CCfields. The broadcast signal transmission apparatus of the presentinvention may delete Sync Byte and a PID using HC_mode3 which is thethird header compression mode. Therefore, after header compression, theTS packet header may include TE, SI, TP, SC, AF and/or SF fields. Inother words, the broadcast signal transmission apparatus does nottransmit Sync Byte and the PID in HC_mode3. In this way, the TS packetheader of 4 bytes may be compressed into 1 byte. The broadcast signaltransmission apparatus may delete the PID corresponding to 13 bits. Inaddition, in HC_mode3, the broadcast signal transmission apparatus mayreplace the CC field with the SF field. The broadcast signaltransmission apparatus may further reduce 3 bits by replacing the CCfield of 4 bits by the SF field of 1 bit. The broadcast signaltransmission apparatus may reduce 3 bytes (24 bits) when compared to theTS packet header to be subjected to compression by deleting Sync Byte toreduce 8 bits, deleting the PID to reduce 13 bits, and replacing the CCfield to reduce 3 bits with respect to the TS packet header. In otherwords, the TS packet header of 4 bytes may be compressed into 1 byte.

FIG. 42 illustrates a forth header compression scheme according to anembodiment of the present invention. A forth header compression mode maybe expressed by HC_mode4. When a header compression mode used for a linklayer packet is HC_mode4, a value of the HC_mode field may be set to 11.In addition, a payload of the link layer packet may include a first TSpacket having 187 bytes which is obtained by excluding Sync byte from aTS packet of 188 bytes. From a second TS packet included in the payload,a TS packet may not include a TS header and may have a total length of184 bytes. In other words, in HC_mode4, a broadcast signal transmittermay delete TS headers of TS packets except for the first TS packetincluded in the payload. This scheme may be used when TS packetsincluded in the link layer packet have the same TS header. In otherwords, the scheme may be used when a plurality of fields included in aTS header have the same value.

In this case, a length of the payload is 184*Num_TS+3 bytes, and a totallength of the link layer packet may be obtained by adding the length ofthe payload to a length of an L2 header (2 or 5 bytes). In other words,a first TS packet header corresponding to a portion of informationtransmitted through the payload may be compressed from 4 bytes into 3bytes and the other TS packet headers may be deleted. As described inthe foregoing, the Num_TS field may indicate the number of TS packetsencapsulated in the link layer.

Hereinafter, a description will be given of null packet deletion. SomeTS input streams or divided TSs may have a great number of null packetsto accommodate a variable bit-rate (VBR) service in a CBR TS. In thiscase, a null packet may be checked and not transmitted to avoidunnecessary transmission overhead. In a receiver, a deleted null packetmay be reinserted into an accurate original place with reference to adeleted null-packet (DNP) counter inserted during transmission, and thusa CBR is ensured and a time stamp (PCR) may not be updated. A nullpacket deletion scheme to be described below may be applied to the nullpacket deletion block 3030 described with reference to FIG. 3.

FIG. 43 illustrates a first null packet deletion scheme according to anembodiment of the present invention. A first null packet deletion modemay be expressed by NPD_mode1. When a null packet deletion mode used fora link layer packet is NPD_mode1, a value of an NPD_mode field may beset to 00. NPD_mode1 is a mode in which null packet deletion is notperformed. In this mode, a null packet may be transmitted through an L2payload, and a DNP may not be present.

FIG. 44 illustrates a second null packet deletion scheme according to anembodiment of the present invention. A second null packet deletion modemay be expressed by NPD_mode2. When a null packet deletion mode used fora link layer packet is NPD_mode2, a value of an NPD_mode field may beset to 01. NPD_mode2 may be used in a case of a high frequency of nullpackets. The broadcast signal transmission apparatus may delete nullpackets using NPD_mode2 and signal the number of deleted null packetsthrough a DNP of 8 bits. The DNP may be inserted between TS packetsincluded in an L2 payload. In other words, the broadcast signaltransmission apparatus may insert each DNP into a tail of a separate TSpacket included in an L2 packet. Here, the DNP may indicate whether adeleted null packet is present between each TS and a subsequent TS andthe number of deleted null packets. Therefore, a DNP positioned betweena first TS packet and a second TS packet may have a value of 0 whenthere is no deleted null packet between the first TS packet and thesecond TS packet, and have a value indicating the number of deleted nullpackets when null packets are deleted. The DNP may have a value within arange of 0 to 255 which is expressed by 1 byte.

The broadcast signal transmission apparatus may delete null packetsamong TS packets and null packets such that a payload included in the L2packet is reduced by a size of the deleted null packets. In addition,the broadcast signal transmission apparatus may insert a DNP of 8 bits(1 byte) between TS packets included in the L2 packet, and a totallength of the L2 packet may increase by a size of the inserted DNPs. Inother words, the total length of the L2 packet may increase by Num_TS*1byte. As illustrated in the figure, a null packet is not present from afirst TS packet to a third TS packet. When one null packet is generatedafter the third TS packet, the broadcast signal transmission apparatusmay set a value of a DNP positioned after the third TS packet to 1. Inaddition, when two null packets are generated after a fourth TS packet,the broadcast signal transmission apparatus may set a value of a DNPpositioned after the fourth TS packet to 2. As described in theforegoing, the broadcast signal transmission apparatus may report thenumber of deleted null packets by signaling the number of deleted nullpackets at a rear of each TS packet using a DNP, and the receiver mayrestore the deleted null packets using a DNP value.

FIG. 45 illustrates a third null packet deletion scheme according to anembodiment of the present invention. A third null packet deletion modemay be expressed by NPD_mode3. When a null packet deletion mode used fora link layer packet is NPD_mode3, a value of an NPD_mode field may beset to 10. NPD_mode3 may be used in a case of a low frequency of nullpackets. The broadcast signal transmission apparatus may merge aplurality of TSs using NPD_mode3 until a null packet is generated.Thereafter, the broadcast signal transmission apparatus may count thenumber of generated null packets and signal the number using a DNP fieldof 8 bits positioned at a tail of a payload of an L2 packet. Here, theDNP field may signal that a maximum of 255 null packets are deleted.

When the broadcast signal transmission apparatus uses NPD_mode3, a totallength of the L2 packet may increase by 1 byte which is a length of theDNP field.

FIG. 46 illustrates a fourth null packet deletion scheme according to anembodiment of the present invention. A fourth null packet deletion modemay be expressed by NPD_mode4. When a null packet deletion mode used fora link layer packet is NPD_mode4, a value of an NPD_mode field may beset to 11. NPD_mode4 may be used in a case of a low frequency of nullpackets. The broadcast signal transmission apparatus may merge aplurality of TSs using NPD_mode4 until a null packet is generated.Thereafter, the broadcast signal transmission apparatus may count thenumber of generated null packets and signal the number using a DNP fieldof 16 bits positioned at a tail of a payload of an L2 packet. Here, theDNP field may signal that a maximum of 65535 null packets are deleted.

When the broadcast signal transmission apparatus uses NPD_mode4, a totallength of the L2 packet may increase by 2 bytes which is a length of theDNP field.

Hereinafter, a description will be given of a configuration of a headerof a baseband frame. Hereinafter, the baseband frame may be referred toas a baseband packet. A configuration of a header of a conventionalbaseband frame has a disadvantage in that data transmission efficiencydecreases when the broadcast signal transmission apparatus has optiondata to be transmitted at all times. The header configuration of thebaseband frame of the present invention has an advantage in that abaseband frame may be efficiently configured using an independentextension field when option data is inserted into each baseband frame.

FIG. 47 illustrates an input format block according to anotherembodiment of the present invention.

The input format block illustrated in FIG. 47 may correspond to anexample of the input format block 1000 described with reference toFIG. 1. The header configuration of the baseband frame of the presentinvention to be described below may be similarly applied to theabove-described input format block or a general input format block inaddition to the input format block described with reference to FIG. 47.

FIG. 47 illustrates a mode adaptation block of the input format block ofthe broadcast signal transmission apparatus according to an embodimentof the present invention.

The mode adaptation block of the input format block for processingmultiple input streams may independently process a plurality of inputstreams.

As illustrated in FIG. 47, the mode adaptation block for separatelyprocessing multiple input streams may include an input stream splitter47010, an input interface 47020, an input stream synchronizer 47030, acompensation delay block 47040, a header compression block 47050, a nulldata reuse block 47060, a null packet deletion block 47070, and/or abaseband header insertion block 47080. In the present specification, theBB header insertion block 47080 may be included in a baseband framingblock or a baseband formatter. The baseband framing block or thebaseband formatter may include a baseband packet generation block, abaseband header insertion block, and a baseband scrambling block. Theabove description with reference to FIGS. 2 and 3 may be similarlyapplied to a description of the respective blocks, and thus adescription of the respective blocks will be omitted. The headerconfiguration of the baseband frame to be described below may be appliedto an operation of the baseband header insertion block 47080 of the modeadaptation block. In other words, hereinafter, a description will begiven of a method of generating a baseband header.

FIG. 48 illustrates a broadcast signal reception apparatus according toan embodiment of the present invention.

The broadcast signal reception apparatus may include a baseband frameheader parser 48010, a null packet insertion block 48020, a null dataregenerator 48030, a header de-compression block 48040, a de-jitterbuffer block 48050, a TS recombining block 48060, and a TS clockregeneration block 48070. A header configuration of a baseband frame ofthe present invention may be used when a baseband header parser parses abaseband frame header. The broadcast signal reception apparatus mayparse the proposed header configuration using the baseband frame headerparser 48010. The null packet insertion block 48020 may reinsert adeleted null packet on a transmitting side. The null data regenerator48030 may regenerate deleted null data, and the header de-compressionblock 48040 may decompress and extract compressed header information.The de-jitter buffer block 48050 may compensate for jitter using the TSclock regeneration block 48070, and recombine TS data which has beenpacketized into a plurality of TS packets using the TS recombining block48060. The broadcast signal reception apparatus may restore and output adata stream through this process. As described in the foregoing, theheader configuration of the baseband frame of the present invention mayindicate the header configuration parsed by the baseband frame headerparser 48010.

FIG. 49 illustrates a packet configuration of a baseband frame accordingto an embodiment of the present invention. In FIG. 49(a), a basebandframe header packetizes a signal (input stream: a TS, an IP stream, anda GS) transmitted through a physical layer in baseband frames such thatthe signal may be input to a BICM block with a suitable length andconfiguration. Hereinafter, the baseband frame header may be referred toas a base field. The baseband frame may include a header part, anoptional part, and a payload part in which an input stream istransmitted. A baseband header (base field) does not have a stuffingbyte. When a value of a SYNCD field is less than 128 bytes, a 1-bytemode is used. When the stuffing byte is present or a value of the SYNCDfield is greater than or equal to 128 bytes, a 2-byte mode may be used.The 1-byte mode may include a MODE field of 1 bit and a SYNCD_LSB fieldof 7 bits. The 2-byte mode may include a SYNCD_MSB field of 6 bits andan OPTI field of 2 bits in addition to the fields of the 1-byte mode. Inthe present specification, the OPTI field may be referred to as an OFIfield.

An option field is an intermittently generated field such as a stuffingfield, an in-band signaling field, an ISSY field, etc. The OPTI fieldmay define a configuration of the option field.

When the option field is present, an OPT header of 1 byte or 2 bytes maybe included. The OPT header may include an OPT_TYPE field of 3 bitsindicating a type, and OPT_LEN_LSB and OPT_LEN_MSB fields indicatinglengths of the option field. Here, a configuration of the OPT_LEN fieldmay be determined based on the OPT_TYPE field.

FIGS. 50 and 51 illustrate configurations of a baseband frame accordingto an embodiment of the present invention.

A baseband frame generated by the broadcast signal transmissionapparatus may have a different configuration depending on cases.

A first case may indicate a configuration of a baseband frame when anOPT field is not present and a value of SYNCD is less than or equal to128 bytes (50010). The baseband frame of the first case may include aMODE field, a SYNCD_LSB field, and a payload field. Here, the MODE fieldmay be set to “0”, and the SYNCD_LSB field may express a SYNCD valuewithin a range of 0 to 127 bytes. In this case, a baseband frame headerhas 1 byte. In other words, as illustrated in FIG. 51, including views(a) and (b), when the MODE field is set to “0”, a baseband header modeof 1 byte may be indicated.

A second case may indicate a configuration of a baseband frame when anOPT field is present, or when an OPT field is not present and a value ofSYNCD is greater than or equal to 128 bytes (50020). Here, a MODE fieldmay be set to “1”, and a SYNCD_LSB field and a SYNCD_MSB field may beused as a value of SYNCD. In addition, an OPTI field of 2 bits may bepresent, and an OPT field may be determined through the OPTI field. Asillustrated in FIG. 51(a), when the MODE field is set to “1”, a basebandheader mode of 2 bytes may be indicated.

Hereinafter, specific cases of the second case will be described.

Case 2-1 may indicate a configuration of a baseband frame when the OPTfield is not present in the 2-byte mode (50021). An OPTI field is set to“00”. In this case, the baseband frame may not include the OPT field. Asillustrated in FIG. 51(b), when the OPTI field is set to “00”, abaseband header mode excluding the OPT field may be indicated.

When a value of SYNCD is greater than or equal to 128 bytes, a basebandframe header may have 2 bytes. In this instance, the baseband frame doesnot include the OPT field, and a payload may be positioned after thebaseband frame header.

When the OPTI field does not correspond to “00”, the baseband frame mayinclude the OPT field. The OPT field may be used to insert a stuffingfield to adjust a data rate or transmit data of another use other than apayload for transmitting input stream data when the baseband frame isconfigured. The data of the other use may include an ISSY field forsynchronization, an in-band signaling field for assistance in L1 (PLS),etc. The data may be transmitted as necessary rather than beingtransmitted in every baseband frame. Hereinafter, a description will begiven of a case in which the baseband frame includes an option field.

Case 2-2 may indicate a configuration of a baseband frame when astuffing (dummy: 0x00 or 0xff) byte of 1 byte is present (50022). Here,an OPTI field may be set to “01”, which may signal that an OPT header of1 byte is used as the stuffing byte. As illustrated in FIG. 51, when theOPTI field is set to “01”, a baseband frame including one stuffing bytemay be indicated. The broadcast signal transmission apparatus may notuse an OPT field to insert the one stuffing byte into the basebandframe, and may insert the one stuffing byte by setting an OPT type fieldto “000” and setting an OPT_LENGTH_LSB field to “00000”.

Case 2-3 may indicate a configuration of a baseband frame when twostuffing bytes are present (50023). Here, an OPTI field may be set to“10”, which may signal that an OPT header of 2 bytes is used as stuffingbytes. As illustrated in FIG. 51, when the OPTI field is set to “10”, abaseband frame including two stuffing bytes may be indicated. Thebroadcast signal transmission apparatus may not use an OPT field toinsert the two stuffing bytes into the baseband frame, and may insertthe two stuffing bytes by setting an OPT type field to “000” and settingeach of an OPT_LENGTH_LSB field and an OPT_LEN_MSB field to “00000000”.

Case 2-4-1 may indicate a configuration of a baseband frame whenstuffing bytes within a range of 2 bytes to 31 bytes are present(50024-1). Here, an OPTI field may be set to “11”, and the broadcastsignal transmission apparatus may fill an OPT header of 2 bytes and anOPT field with stuffing bytes (dummy bytes). As illustrated in FIG. 51,when the OPTI field is set to “11”, a baseband frame including the OPTfield and the stuffing bytes may be indicated. The broadcast signaltransmission apparatus may set an OPT type to “000” to insert stuffingbytes within a range of 2 bytes to 31 bytes into the baseband frame,indicate a length of the OPT field using an OPT_LENGTH_LSB field, andinsert stuffing bytes corresponding to a length of the OPT field.

Case 2-4-2 may indicate a configuration of a baseband frame when 32stuffing bytes or more are present (50024-2). Here, an OPTI field may beset to “11”, and the broadcast signal transmission apparatus may fill anOPT header of 2 bytes and an OPT field with stuffing bytes (dummybytes). The broadcast signal transmission apparatus may set an OPT typeto “000” to insert 32 stuffing bytes or more into the baseband frame,indicate a length of the OPT field using an OPT_LENGTH field, and insertstuffing bytes corresponding to a length of the OPT field.

The length of the OPT field may be expressed using an OPT_LEN_LSB fieldand an OPT_LEN_MSB field.

The OPT field included in the baseband frame of Case 2-4-1 and Case2-4-2 may include information necessary for the baseband frame such asISSY, in-band signaling, etc. according to OPT_TYPE in addition to agreat number of stuffing bytes.

FIG. 52 illustrates a packet configuration of a baseband frame accordingto another embodiment of the present invention. The above-describedbaseband frame configuration may efficiently transmit data by minimizinga header configuration. The above-described baseband frame configurationmay be implemented by a header of 2 bytes when stuffing and optioninformation (ISSY, in-band signaling, etc.) are not present. Inparticular, when a value of SYNCD is less than or equal to 127 bytes,the broadcast signal transmission apparatus may operate the basebandframe header using 1 byte. In addition, ISSY and in-band signalingcorresponding to option information may be inserted into an OTP field ofa desired baseband frame using OPT_TYPE.

However, in the above-described baseband frame header configuration,data may be inefficiently transmitted when data is transmitted in an OPTfield of every baseband frame. In this case, every baseband frame headerhas an option field of 2 bytes irrespective of a size of SYNCD. Whenoption information is present other than data to be inserted each time,the broadcast signal transmission apparatus may have difficulty inoperating OPT_TYPE of 3 bits which can express only eight cases.

To solve this problem, it is possible to propose an extension field in abaseband frame as in FIG. 52. In other words, a header of a basebandpacket may include a base field, an option field, and an extensionfield.

The extension field may be used when data to be inserted into everybaseband frame is present. In other words, the broadcast signaltransmission apparatus may position an extension field in a basebandframe and transmit data to be inserted into every baseband frame throughthe extension field, thereby operating the extension field independentlyof the option field. Here, the data to be inserted into every basebandframe may include channel bonding information.

The extension field may be positioned after the baseband frame header inthe baseband frame. The extension field may be positioned before theoption field or the payload in the baseband frame.

FIG. 53 including views (a) and (b), illustrates a signaling field thatsignals a configuration of a baseband frame according to an embodimentof the present invention.

Hereinafter, a description will be given of a signaling scheme usingPLS. A position in a baseband frame header into which an independentextension field is inserted may be a tail of a basic baseband frameheader of 1 or 2 bytes. In this way, a receiver receiving a broadcastsignal may directly parse the extension field without being affected byan option field.

In the present invention, information about the presence/absence of theextension field and information about a type and a length of theextension field may be indicated such that the broadcast signaltransmission apparatus may independently operate the extension field.The broadcast signal transmission apparatus may transmit the informationusing PLS. In the above-described baseband frame scheme, a type of datatransmitted through a payload may be defined for a header of 1 to 2bytes.

FIG. 53(a) illustrates a signaling table of a first type.

A signaling field for input formatting may include information about adata type, an extension field indicator, an extension field type and/oran extension field length.

A data type signal may be referred to as data_type, and 3 bits may beallocated thereto. The data type signal may signal whether transmitteddata is an MPEG2-TS, an IP (v4, v6) stream, or a GS.

The signaling table may include a signaling field for the extensionfield after the data type. Examples of information necessary to use theextension field include information indicating whether the extensionfield is used and information indicating a field type and a field lengthof the extension field.

The information indicating whether the extension field is used may bereferred to as Extension_field_indicator, and 1 bit may be allocatedthereto. The field signals whether the extension field is present in abaseband frame. The field may be set to “0” when the extension field isnot used, and set to “1” when the extension field is used.

The information about the field type of the extension field may bereferred to as Extension_field_type, and 4 bits may be allocatedthereto. Extension_field_type indicates a type of informationtransmitted in extension_field. Extension_field_type may indicate ISSY,CRC, channel bonding information, etc. to be transmitted each time inthe baseband frame.

The information about the field length of the extension field may bereferred to as Extension_field_length, and 13 bits may be allocatedthereto. Extension_field_length may indicate a length of the extensionfield.

For example, when ISSY data of 4 bytes is transmitted in every basebandframe, Extension_field_indicator may be set to “1”, extension_field_typemay be set to “0” which indicates ISSY, and extension_field_length maybe set to “4” which indicates 4 bytes.

FIG. 53(b) illustrates a signaling table of a second type.

The second type corresponds to a scheme of only using theabove-described extension_field_type of 4 bits. When the broadcastsignal transmission apparatus does not use extension_field,extension_field_type may be set to “0” to replace a function ofextension_field_indicator. When the broadcast signal transmissionapparatus uses extension_field, used extension_field_type may indicate atype of the extension field, and a length of the extension field may beset to a predefined length according to type of the extension field.

In the above-described first type, when the extension field is notpresent, extension_field_indicator occupies only 1 bit in PLS, and thusan efficient operation may be performed.

However, a field configuration varies depending on whether the extensionfield is present, and thus the first type is suitable for a variable PLSconfiguration. In other words, while the field occupies 18 bits when theextension field is present, the field may occupy only 1 bit when theextension field is not present.

In the above-described second type, a PLS field size (4 bits) is thesame irrespective of whether the extension field is present in PLS.Therefore, the second type is suitable for a PLS configuration having afixed size.

FIG. 54 illustrates a configuration of a baseband frame according to anembodiment of the present invention.

In a scheme of not using an extension field, data to be inserted intoevery baseband frame may be inserted into an option field. In this case,a header of every baseband frame has 2 bytes, and there may bedifficulty in inserting another option field.

However, when an extension field of the present invention is used, theextension field is separated from an option field, and thus data may beefficiently managed.

When a value of SYNCD is less than or equal to 127 bytes as in a firstbaseband frame, a second baseband frame, and a third baseband frameillustrated in FIG. 54, a baseband frame header of 1 byte may be usedeven when the extension field is included.

In a fourth baseband frame and a fifth baseband frame, a value of SYNCDis greater than 127 bytes, and a baseband frame header has 2 bytessimilarly to the scheme of not using the extension field.

In a sixth baseband frame and a seventh baseband frame, an option fieldand an extension field may coexist.

As described in the foregoing, in the baseband frame configuration ofthe present invention, when data to be inserted into every basebandframe is present, the data may be transmitted using an extension fieldwithout using an option field. Therefore, when CRC is inserted into aheader of the baseband frame, channel bonding information or an ISSYmode, an independent extension field may be used to enhance datatransmission efficiency.

FIG. 55 illustrates a method of transmitting a broadcast signalaccording to an embodiment of the present invention. The broadcastsignal transmission apparatus may input-format input data (S55010).

The broadcast signal transmission apparatus may encapsulate the inputdata. The broadcast signal transmission apparatus may use theabove-described TS header compression scheme in an encapsulationprocess. In other words, as described in the foregoing, the broadcastsignal transmission apparatus may compress a TS header by deleting Syncbyte, compressing a PID, deleting a PID, or deleting a TS header.

In addition, the broadcast signal transmission apparatus may use theabove-described null packet deletion scheme in the encapsulationprocess. In other words, as described in the foregoing, the broadcastsignal transmission apparatus may delete a null packet and add a DNP toevery TS packet, thereby configuring a payload, or add a DNP only when anull packet is generated, thereby deleting the null packet. As describedin the foregoing, a DNP may signal the number of deleted null packets.

The broadcast signal transmission apparatus may build a baseband frameincluding encapsulated input data. In the present specification, thebaseband frame may be expressed by a baseband packet. The broadcastsignal transmission apparatus may use the above-described baseband frameconfiguration in a process of generating a baseband frame. In otherwords, as described in the foregoing, the broadcast signal transmissionapparatus may define an extension field and position the extension fieldin the baseband frame. The broadcast signal transmission apparatus maytransmit data to be inserted into every baseband frame using theextension field. In this way, the broadcast signal transmissionapparatus may transmit data, which is to be transmitted through anoption field, through the extension field, and enhance data transmissionefficiency.

The broadcast signal transmission apparatus may encode formatted inputdata (S55020).

The broadcast signal transmission apparatus may perform encoding usingthe above-described BICM block. Input data which is delivered from aninput formatter to the BICM block may be input as the above-describedPLP data format.

The broadcast signal transmission apparatus may modulate the encodeddata (S55030).

The broadcast signal transmission apparatus may modulate the encodeddata using the above-described OFDM generation block. The encoded datamay be modulated using an OFDM modulation scheme.

The broadcast signal transmission apparatus may transmit a broadcastsignal including the modulated data (S55040). The broadcast signaltransmission apparatus may transmit the modulated data using an outputantenna.

FIG. 56 illustrates a method of receiving a broadcast signal accordingto an embodiment of the present invention.

The broadcast signal reception apparatus may receive a broadcast signal(S56010). The broadcast signal reception apparatus may receive thebroadcast signal using a tuner. The received broadcast signal mayinclude data encapsulated by the broadcast signal transmissionapparatus. The above-described TS header compression scheme may be usedin a process of encapsulating the received broadcast signal. In otherwords, the received broadcast signal may include a TS header which iscompressed by deleting Sync byte, compressing a PID, deleting a PID, ordeleting a TS header.

In addition, the received broadcast signal may be subjected to the nullpacket deletion scheme in the encapsulation process. In other words, asdescribed in the foregoing, the received broadcast signal may correspondto a broadcast signal obtained by deleting a null packet and adding aDNP to every TS packet to configure a payload, or adding a DNP only whena null packet is generated to delete the null packet. As described inthe foregoing, a DNP may signal the number of deleted null packets.

The received broadcast signal may include a baseband frame, and theabove-described baseband frame configuration may be used in a process ofgenerating the baseband frame. In other words, the received broadcastsignal may include a baseband frame having an extension field. Thereceived broadcast signal may include data to be inserted into everybaseband frame in the extension field. In this way, the receivedbroadcast signal may include data, which is to be included in an optionfield, in the extension field, thereby enhancing data transmissionefficiency.

The broadcast signal reception apparatus may demodulate data included inthe broadcast signal (S56020). The broadcast signal reception apparatusmay demodulate data using an OFDM demodulation scheme.

The broadcast signal reception apparatus may decode the demodulated data(S56030).

The broadcast signal reception apparatus may decode the demodulated datausing the above-described decoding module.

The broadcast signal reception apparatus acquire a data stream byoutput-processing the decoded data (S56040). The broadcast signalreception apparatus may acquire and output a data stream using theabove-described output processor. The broadcast signal receptionapparatus may output-process the decoded data using the outputprocessor. The output processor may correspond to the above-describedoutput processor of FIG. 9. In addition, the output processor mayinclude the blocks described with reference to FIG. 48. That is, theoutput processor may include at least one of a baseband frame headerparser, a null packet insertion block, a null data generator, a headerde-compression block, a de-jitter buffer block, and/or a TS recombiningblock. The baseband frame header parser may parse an extension field inthe above-described baseband frame header. Here, the baseband frameheader parser may parse the extension field in the header using theabove-described information that indicates whether an extension field ispresent. As described in the foregoing, the baseband frame may beexpressed by a baseband packet. In addition, the null packet insertionblock may restore a null packet deleted in the receiver using a schemecorresponding to the above-described null packet deletion scheme. Asdescribed in the foregoing, the null packet insertion block may checkthe number of deleted null packets using DNP information that indicatesthe number of deleted null packets, and insert the deleted null packets.In addition, the header de-compression block may restore headerinformation to be subjected to header compression in the receiverthrough a reverse process of the above-described header compressionscheme. The header de-compression block may check a header compressionmode using information about the above-described header compression modeand execute a header de-compression operation according to the mode.

As described in the foregoing, it is possible to enhance datatransmission efficiency using the header compression scheme, the nullpacket deletion scheme, and the extension field generation scheme of thepresent invention.

It will be appreciated by those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

Both apparatus and method inventions are mentioned in this specificationand descriptions of both of the apparatus and method inventions may becomplementarily applicable to each other.

What is claimed is:
 1. A method for receiving broadcast signals, themethod comprising: receiving the broadcast signals; demodulating thereceived broadcast signals by an Orthogonal Frequency Division Multiplex(OFDM) scheme; parsing a signal frame from the demodulated broadcastsignals; decoding data in the parsed signal frame to output basebandpackets; and output-processing the baseband packets to output TransportStream (TS) packets, wherein the baseband packets include link layerpackets to which an encapsulation is applied, wherein each header of thelink layer packets includes first information indicating whether aheader deletion is performed on the TS packets, and wherein theoutput-processing includes inserting a header for each TS packet ofwhich a header is deleted based on the first information.
 2. The methodof claim 1, wherein the output-processing further includes inserting async byte into a header of each of the TS packets.
 3. The method ofclaim 1, wherein a header of each of the baseband packets includes anextension field which extends the header of the each of the basebandpackets.
 4. An apparatus for receiving broadcast signals, the apparatuscomprising: a receiver to receive the broadcast signals; a demodulatorto demodulate the received broadcast signals by an Orthogonal FrequencyDivision Multiplex (OFDM) scheme; a frame parser to parse a signal framefrom the demodulated broadcast signals; a decoder to decode data in theparsed signal frame to output baseband packets; and an output-processorto output-process the baseband packets to output Transport Stream (TS)packets, wherein the baseband packets include link layer packets towhich an encapsulation is applied, wherein each header of the link layerpackets includes first information indicating whether a header deletionis performed on the TS packets, and wherein the output-processor insertsa header for each TS packet of which a header is deleted based on thefirst information.
 5. The apparatus of claim 4, wherein theoutput-processor further inserts a sync byte into a header of each ofthe TS packets.
 6. The apparatus of claim 4, wherein a header of each ofthe baseband packets includes an extension field which extends theheader of the each of the baseband packets.